This application is based on and claims priority to Japanese Patent Applications No. 2000-284753, filed Sep. 20, 2000, No. 2001-108382, filed Apr. 6, 2001 and No. 2001-276355, filed Sep. 12, 2001, the entire contents of which are hereby expressly incorporated by reference.
1. Field of the Invention
The present invention relates generally to an ventilation system for a watercraft engine, and more particularly to an improved induction system which includes a vapor return system.
2. Description of Related Art
Personal watercraft have become very popular in recent years. This type of watercraft is quite sporting in nature and carries one or more riders. A relatively small hull of the personal watercraft defines a rider""s area above an engine compartment. An internal combustion engine powers a jet propulsion unit which propels the watercraft. The engine lies within the engine compartment in front of a tunnel formed on the underside of the hull. A jet propulsion unit, which includes an impeller, is placed within the tunnel. The impeller has an impeller shaft driven by the engine. The impeller shaft extends between the engine and the jet propulsion device through a bulkhead of the hull tunnel.
Typically, two-cycle engines are used in personal watercraft because two-cycle engines have a fairly high power to weight ratio. One disadvantage of two-cycle engines, however, is that they produce relatively high emissions. In particular, large amounts of carbon monoxide and hydrocarbons are produced during operation of the engine. When steps are taken to reduce these emissions, other undesirable consequences typically result, such as an increase in weight of the engine, the cost of manufacture, and/or the reduction of power.
It has been suggested that four-cycle engines replace two-cycle engines in personal watercraft. Four-cycle engines typically produce less hydrocarbon emissions an two-cycle engines while still producing a relatively high power output. However, adapting four-cycle engines for use in personal watercraft has its own engineering and technical challenges due to, at least in part, the limited space available within the hull of a personal watercraft.
A four-cycle engine utilizes a more complex lubrication system as compared with a two-cycle engine. One approach to enabling the use of a four-cycle engine in personal watercraft applications is to provide the engine with a dry sump lubrication system. A dry sump system utilizes a shallow reservoir of oil available for an oil pump as compared with the volume of oil in a wet sump system having an oil pan, thus reducing the overall height of the engine.
A four-cycle engine can also utilize a ventilation system through which blow-by gases are returned to an air induction system to be burned with an air/fuel charge in one or more combustion chambers. The blow-by gases are comprised of air/fuel mixture and/or oil leaking from a combustion chamber into the crankcase through a nominal space formed between a piston and an inner surface of a cylinder bore.
FIG. 1 illustrates a diagrammatic view of an exemplary arrangement that includes a combined lubrication and ventilation system. It should be noted that the arrangement shown in FIG. 1 is not prior art and was developed by the inventors themselves. While the engine 28 is operating, lubricant oil that has lubricated engine portions and blow-by gases together drain downwardly to a shallow reservoir defined in the crankcase 30 of the engine 28. A scavenge pump 32 pressurizes the oil and the blow-by gases to an oil tank assembly 34 through a scavenge passage 36. A feed pump 38 pressurizes and thereby feeds the oil in the oil tank assembly 34 to the engine portions that need lubrication through a feed passage 40. If the oil in the oil tank assembly 34 exceeds a preset level, the excess oil moves to a cylinder head 42 through a spillway passage 44 and thus lubricates engine components therein.
A plenum chamber 46 is coupled with the combustion chamber defined within the cylinder head 42 through an intake passage. The blow-by gases collected in the oil tank assembly 34 are drawn into the plenum chamber 46 through a ventilation passage 50 and then to the combustion chamber with a fresh air/fuel charge to be burned therein. This cycle repeats as the engine 28 operates.
One aspect of the present invention includes the realization that the arrangement illustrated in FIG. 1 can cause a problem if used with a personal watercraft. Typically, personal watercraft are capsized and readily returned to a normal upright position during operation. However, in the arrangement thus described, the oil in the oil tank assembly 34 can flow into the ventilation passage 50 and then to the plenum chamber 46 while the watercraft capsizing. If this occurs, an air induction system including the plenum chamber 46 and the intake passage 48 can be damaged by the oil flown thereinto. Additionally, such a flow of oil into the induction system can interfere with normal operation of the engine. A need thus exists for an improved ventilation system for a watercraft engine that can inhibit the oil from flowing into an air induction system even if the watercraft capsizes.
In accordance with another aspect of the present invention, a watercraft comprises a hull. A propulsion device is configured to propel the hull. An internal combustion engine is configured to power the propulsion device. The engine includes an engine body and a moveable member moveable relative to the engine body. The engine body and the moveable member together define a combustion chamber. An air induction system is configured to guide air to the combustion chamber. A lubrication system is arranged to lubricate at least a portion of the engine body with lubricant oil. The lubrication system includes an oil container out of the engine body. A ventilation system is configured to separate a gaseous component from a liquid component. The ventilation system includes a separator configured to separate the gaseous component from the liquid component. A ventilation passage connects the separator with the air induction system. A return passage couples a bottom portion of the ventilation passage with inside of the engine body.
In accordance with yet another aspect of the present invention, a watercraft comprises a hull. A propulsion device is arranged to propel the hull. An internal combustion engine is arranged to power the propulsion device. The engine includes an engine body and a moveable member moveable relative to the engine body. The engine body and the moveable member together define a combustion chamber. An air induction system is arranged to introduce air to the combustion chamber. A lubrication system is arranged to lubricate at least a portion of the engine body with lubricant oil. The lubrication system includes an oil container out of the engine body. A ventilation system is arranged to separate a gaseous component from a liquid component. The ventilation system includes a separator configured to separate the gaseous component from the liquid component. A ventilation passage connects the separator with the air induction system. An upstream end of the ventilation passages is disposed on one side of the hull. At least a portion of the ventilation passage is disposed on the other side of the hull.
In accordance with a further aspect of the present invention, a watercraft comprises a hull. A propulsion device is arranged to propel the hull. An internal combustion engine is arranged to power the propulsion device. The engine includes an engine body and a moveable member moveable relative to the engine body. The engine body and the moveable member together define a combustion chamber. An air induction system is arranged to introduce air to the combustion chamber. A lubrication system is arranged to lubricate at least a portion of the engine body with lubricant oil. The lubrication system includes an oil container out of the engine body. A ventilation system is arranged to separate a gaseous component from a liquid component. The ventilation system includes a separator configured to separate the gaseous component from the liquid component. A ventilation passage connects the separator with the air induction system. A check valve is disposed within the ventilation passage. The check valve is configured to open when the watercraft is in a normal upright position and to close when the watercraft is in a capsizing position.
In accordance with a still further aspect of the present invention, a watercraft comprises a hull. A propulsion device is configured to propel the hull. An internal combustion engine is configured to power the propulsion device. The engine includes an engine body and a moveable member moveable relative to the engine body. The engine body and the moveable member together define a combustion chamber. An air induction system is configured to guide air to the combustion chamber. A lubrication system is configured to lubricate at least a portion of the engine body with lubricant oil. The engine body defines a space in which the oil that has lubricated the portion of the engine body temporarily collects. The lubrication system includes an oil container out of the engine body. A scavenge passage couples the space with the oil container. A ventilation system is configured to separate a gaseous component from a liquid component. The ventilation system includes a separator configured to separate the gaseous component from the liquid component. A ventilation passage connects the separator with the air induction system. A return passage couples the ventilation passage with inside of the engine body. The return passage is connected with the scavenge passage.
In accordance with a yet further aspect of the present invention, a watercraft comprises a hull. A propulsion device is configured to propel the hull. An internal combustion engine is configured to power the propulsion device. The engine includes an engine body and a moveable member moveable relative to the engine body. The engine body and the moveable member together define a combustion chamber. An air induction system is configured to introduce air to the combustion chamber. A lubrication system is configured to lubricate at least a portion of the engine body with lubricant oil. The lubrication system includes an oil container out of the engine body. A ventilation system is configured to separate a gaseous component from a liquid component. The ventilation system includes a plurality of separators configured to separate the gaseous component from the liquid component. A ventilation passage connects the separators with the air induction system. A return passage couples the ventilation passage with inside of the engine body.